In the alveolar region of the lung where gas exchange occurs, the liquid lining contains a surfactant which acts to lower the surface tension by aligning the long organic chains at the air-water interface. The major components of this pulmonary surfactant (PS) are phosphatidylcholines, in which as much as 30% of the fatty acids are unsaturated. These organics thus present a potential reaction site for inhaled oxidant air pollutants such as ozone. While inhalation of 03 is known to cause a change in the PS, and specifically in the fatty acid composition, it is not known whether this is due to a direct chemical reaction of 03 with the unsaturated fatty acids or to changes associated with the well-known inflammatory response occurring 24-48 hours after the exposure. The aims of this research are to determine whether 03 reacts with unsaturated phospholipids found in PS when they are a monolayer at the air-water interface, to identify the intermediates and products of the reactions, and to assess the effects of the reactions on the surface tension-reducing properties of the surfactant. From these studies, the potential role of such reactions in initiating the inflammatory response can be assessed. The MBRS students will participate fully in the conceptual development of the project, in the experimental design, in the experiments themselves, including data analysis, and finally in publication of the results. Specifically, they will carry out in vitro studies of the reactions of model compounds using a Langmuir-Blodgett film balance recently constructed and tested in our laboratory. In addition, they will isolate PS from rats and study the effects of ozone on the PS both in vitro and in vivo.